Rotoscoping

Patent drawing for Fleischer's original rotoscope. The artist is drawing on a transparent easel, onto which the movie projector at the right is throwing an image of a single film frame.

Rotoscoping is an animation technique in which animators trace over footage, frame by frame, for use in live-action and animated films.[1][2] Originally, recorded live-action film images were projected onto a frosted glass panel and re-drawn by an animator. This projection equipment is called a rotoscope. Although this device was eventually replaced by computers, the process is still referred to as rotoscoping.

In the visual effects industry, the term rotoscoping refers to the technique of manually creating a matte for an element on a live-action plate so it may be composited over another background.

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The technique was invented by cartoonist/illustrator/writer/inventor Max Fleischer, who used it in his technologically groundbreaking, Out of the Inkwell (debut: 1915) animated series. The live-film reference for the series' main cartoon/animated character, Koko the Clown, was supplied by one of his brothers (Dave Fleischer) -- performing choreographed movements while dressed in a clown outfit. Max Fleischer patented the rotoscope method in 1917.[3]

Max Fleischer used rotoscoping in a number of his later cartoons, most notably the Cab Calloway dance routines in three Betty Boop cartoons from the early 1930s, and the animation of Gulliver in Gulliver's Travels (1939). Fleischer's animation studio's most effective and revered use of rotoscoping was in its series of short-length, action-oriented, film noir-styled Superman cartoons of the early-1940s, in which Superman and the other animated characters displayed shockingly realistic bodily movement (on a level unmatched by later, conventional forms of cartoon animation).

Ralph Bakshi used the technique extensively in his animated movies Wizards (1977), The Lord of the Rings (1978), American Pop[1] (1981), and Fire and Ice (1983). Bakshi first turned to rotoscoping because 20th Century Fox refused his request for a $50,000 budget increase to finish Wizards, and he resorted to the rotoscope technique to finish the battle sequences.[5][6]

In the mid-1990s, Bob Sabiston, an animator and computer scientist veteran of the MITMedia Lab, developed a computer-assisted "interpolated rotoscoping" process, which he used to make his award-winning short film "Snack and Drink". Director Richard Linklater subsequently employed Sabiston and his proprietary Rotoshop software in the full-length feature films Waking Life (2001) and A Scanner Darkly (2006).[7] Linklater licensed the same proprietary rotoscoping process for the look of both films. Linklater is the first director to use digital rotoscoping to create an entire feature film. Additionally, a 2005–08 advertising campaign by Charles Schwab uses Sabiston's rotoscoping work for a series of television spots, under the tagline "Talk to Chuck".

In 2013, the animeThe Flowers of Evil was criticized by viewers for using rotoscoping to produce a look that differed greatly from its manga source material. They criticized shortcuts in animating facial features, reusing several backgrounds, and taking liberties in realism. Despite this, critics lauded the anime. The website Anime News Network awarded it a perfect score for initial reactions.[8]

Rotoscope output can have slight deviations from the true line that differs from frame to frame, which when animated cause the animated line to shake unnaturally, or "boil". Avoiding boiling requires considerable skill in the person performing the tracing, though causing the "boil" intentionally is a stylistic technique sometimes used to emphasize the surreal quality of rotoscoping, as in the music video "Take On Me" and animated TV series Delta State. The very first animated music video "Routine Day", was rotoscoped. Created for the band "Klaatu" by Al Guest and Jean Mathieson, it employed overlapping dissolves to give a dream-like feeling to the "boiling" pencil line. The technique was also used for the Kansas video "All I Wanted".

Rotoscoping (often abbreviated as "roto") has often been used as a tool for visual effects in live-action movies. By tracing an object, a silhouette (called a matte) is created that can be used to extract that object from a scene for use on a different background. While blue and green screen techniques have made the process of layering subjects in scenes easier, rotoscoping still plays a large role in the production of visual effects imagery. Rotoscoping in the digital domain is often aided by motion tracking and onion-skinning software. Rotoscoping is often used in the preparation of garbage mattes for other matte-pulling processes.

Rotoscoping has also been used to allow a special visual effect (such as a glow, for example) to be guided by the matte or rotoscoped line. One classic use of traditional rotoscoping was in the original three Star Wars films, where it was used to create the glowing lightsaber effect, by creating a matte based on sticks held by the actors. To achieve this, editors traced a line over each frame with the prop, then enlarged each line and added the glow.